Bad locking with MS-Access

Hello !

I made the port of an Access 2002 Database to PostgreSQL 8, it seems to work.
I still use MS-Access 2002 for the application, using ODBC with linked tables.

For all the data created BEFORE the transfert to PostgreSQL, all works fine.
For the records created SINCE this transfert, it is impossible to modify or delete these records !?
MS-Access say that "The record is acceded by an other user", even I am the only user.

I look for the the options / advanced tab of that MS-database, I don't find an issue.
I look for the parameters of my ODBC system daya source without success.
I don't find any solution with PostgreSQL...

BUT if I modify any field in one of these locked records with the browser of pgAdmin III,
then MS-Access accept to modify or delete the corresponding record !?
If I write an SQL script to do the same in pgAdmin III (ex. add zero to an integer value),
it don't works !

I'm going crazy !...
HELP !

Luc